Yarn brake for twined yarns



NOV. 17, 1970 3,540,202

YARN BRAKE FOR TWINED YARNS Filed Aug. 26, 1968 INVENTOR. GEERT JAN VERMEULEN Map/5m ATTORN EYS I United States Patent 3,540,202 YARN BRAKE FOR TWINED YARNS Geert Jan Vermeulen, Deurne, Netherlands, assignor t0 N.V. Machinefabriek L. te Strake, Deurne, Netherlands, a corporation of the Netherlands Filed Aug. 26, 1968, Ser. No. 755,337 Claims priority, application Netherlands, Sept. 12, 1967, 6712483 Int. Cl. B65h 59/10; D01h 13/08, 13/10 US. Cl. 57-106 4 Claims ABSTRACT OF THE DISCLOSURE A yarn brake for twined yarns comprising a pair of relatively movable yarn guides each having yarn guide formations such as pins or eyelets. One yarn guide is fixed and the other guide biassed such that it tends to move away from the fixed guide. The movable guide is mechanically coupled to a coil in a magnetic field which is energized from an alternating current source with adjustable frequency and amplitude. The coil imparts to the movable yarn guide an adjustable vibration relative to the other yarn guide which periodically allows the twist of the yarn to pass through the yarn brake thereby opposing any back-up of twist.

The invention relates to a yarn brake for twined yarns, comprising a first yarn guide with pins or eyelets, which is so biassed with respect to a second yarn guide with pins or eyelets, that it tends to move away from the second yarn guide.

With such yarn brakes, the output tension in a yarn can be made substantially independent of variations of the input tension, but these yarn brakes in general have the disadvantage that back-up of twist occurs with twined yarns. The twist which initially is distributed evenly along the length of the yarn, is shifted by the friction which the yarn experiences in the yarn brake, until the friction of the yarn has increased to such an extent, that it becomes able to surmount the friction in the yarn brake, whereupon the twist passes through the yarn brake. Thereby, the yarn leaving the yarn brake exhibits twist packages at some distance from one another, which is obviously undesirable.

The invention aims at providing a yarn brake which is not subject to this disadvantage.

For that purpose, it is a feature of a yarn brake according to the invention, that it is provided with a coil in a magnetic field, which is coupled with the first yarn guide and is connected to an alternating current source with adjustable frequency and amplitude, whereby the coil imparts a vibration which is adjustable in frequency and amplitude to the first yarn guide with respect to the second yarn guide, whereby back-up of twist is opposed.

Due to the alternating current which is applied to the coil, the yarn brake opens and closes in an adjustable rhythm and to an adjustable degree, whereby the twist is enabled with sufficiently short intervals to pass through the yarn brake, so that no back-up of twist occurs. Obviously, the amplitude of the alternating current must be kept sufliciently small for maintaing the'sta'bilizing influence of the yarn brake on the tension in the yarn after the yarn brake.

The invention is further elucidated below with reference to the drawing, which shows an embodiment of a yarn brake according to the invention.

FIG. 1 is a diagram of a yarn with evenly distributed twist.

FIG. 2 is a diagram of a yarn in which back-up of twist has occurred.

FIG. 3 is a block diagram of a yarn brack according to the invention.

An evenly twisted yarn in general has a configuration as shown in FIG. 1 and this configuration should be 'lranaiiitained also after passing the yarn through the yarn ra e.

However, with known yarn brakes, back-up of twist is usually encountered, whereby the twist after the yarn has passed through the yarn brake is divided into twist packages 1 as shown in FIG. 2, between which there are yarn sections 2 in which no or substantially no twist is present. A yarn with back-up of twist is obviously of inferior quality, compared with a yarn with evenly distributed twist, and may even be entirely useless.

The occurrence of back-up of twist can be prevented with a device as shown in FIG. 3, in which the twisted yarn 3 is slung around the pins 4 of a first yarn guide 5 and the pins 6 of a movable second yarn guide 7. The pins 4 and 6 can be replaced by eyelets through which the yarn 3 is passed. The movable yarn guide 7 is so biassed with respect to the fixed yarn guide 5, that it tends to move away from the fixed yarn guide.

For preventing back-up of twist, the movable yarn guide 7 is coupled with a coil 8 in a magnetic field, e.g. designed as a moving coil to which an alternating current is applied for an alternating current source 9 with adjustable frequency, through a rheostat 10 for adjusting the amplitude. The coil 8 and the yarn guide 7 coupled with it thereby vibrate with respect to the fixed yarn guide 5. This vibration opens and closes the yarn brake at a high rate, whereby the twist of the yarn 3 is periodically allowed to pass through the yarn brake without back-up occurring. The frequency of the alternating current source 9 must obviously be higher as the speed of the yarn 3 and the twist pitch are higher. A good operation is in most cases ensured if the frequency of the alternating current source 9 is chosen so high, that the yarn during a period of the alternating current moves along a distance not exceeding the distance over which a half twist revolution in the yarn 3 occurs.

The bias of the movable yarn guide 7 can generally be obtained in any desired way. Due to the presence of the coil 8 with a view to the vibration to be imparted to the yarn guide 7, there is a possibility of effecting the bias by applying not only an alternating current to the coil 8, but also a direct current, which can be supplied e.g. by a direct current source 11 through a rheostat 12. In this way, a very simple yarn brake can be obtained, which causes no or almost no back-up of twist.

What is claimed is:

1. A yarn brake for twined yarns, comprising a pair of yarn guides each having yarn guide formations, one of said yarn guides being so biassed with respect to the other that it tends to move away from said other yarn guide, a coil in a magnetic field coupled with said one yarn guide and connected to an alternating current source with adjustable frequency and amplitude, whereby the coil imparts to said one yarn guide a vibration relative to said other yarn guide which is adjustable in frequency References Cited and amplitude, whereby back-up of twist is opposed. UNITED STATES PATENTS 2. A yarn brake according to claim 1, wherein the coil comprises a moving 601 2,943,377 7/1960 Frciber ger 28-12 3. A yarn brake according to claim 2, wherein the 3,067,563 12/1962 Van D131? 57 34 5 3,238,591 3/1966 Rosenstem 281.6

coil is also connected to an adjustable direct current source and thereby provides the bias of the first yarn O PETRAKES, Primary Examiner guide.

4. A yarn brake according to claim 1, wherein the coil 242 153 is also connected to an adjustable direct current source and thereby provides the bias of the first yarn guide. 

